Facile synthesis of dual-ligand terbium-organic gels as ratiometric fluorescence probes for efficient mercury detection

Mercury (Hg) pollution can negatively impact ecosystems, and there is a need for simple Hg2+ monitoring platforms. Here, a dual-ligand fluorescence probe based on terbium-organic gels (Tb-L0.2P0.8 MOGs) was constructed for efficient Hg2+ detection. Tb-L0.2P0.8 MOGs were developed through a facile room-temperature gelation method, showing two emission peaks derived from luminol and Tb3+ at 424 nm and 544 nm, respectively. The aggregation-induced emission (AIE) effect between luminol and Tb3+ led to luminol with blue fluorescence. However, Hg2+ could dramatically quench the fluorescence signal of luminol at 424 nm because of the intense coordination interaction of Hg2+ with luminol and photo-induced electron transfer (PET). The Phen ligand could sensitize the luminescence of Tb3+ and offer a reference fluorescence, thus resulting in a unique ratiometric fluorescence response toward Hg2+. This novel nanoprobe had excellent linearity with Hg2+ concentrations range of 0.1-30 μM; the detection limit was 3.6 nM. The analysis of real samples showed the potential application of MOGs for measuring Hg2+ in porphyra and tap water. Mixed ligands were introduced for high-efficiency strategies to improve the analytical performance by regulating the emission behavior of MOGs.